The present invention relates to a wideband directional antenna; and, more particularly, a wideband directional antenna using a radiation element of a skeleton slot or a delta slot.
Generally, a dipole radiation element or a partially transformed dipole radiation element has been used as a radiation element of a conventional antenna in mobile communication base stations.
FIG. 1 is a perspective view showing a conventional dipole array directional antenna. The conventional dipole array antenna includes a reflector 11, choke reflectors 12, a feeding cable 13 and a power divider 14. Four dipole elements 15 are disposed in a 2xc3x972 array on the reflector 11 for embodying a horizontal beamwidth of about 40 degrees to 65 degrees. Signals inputted from the feeding cable 13 are divided to each dipole element 15 through the power divider 14. Also, the choke reflectors 12 located on both sides of the reflector 11 in a longitudinal direction has an effect on suppression of side lobes in the antenna by suppressing undesired radiation to both sides of the antenna.
However, these dipole elements for radiation have a narrow bandwidth of below 10%. When the dipole elements are used in the directional antenna, a variation of beamwidth becomes larger according to a frequency of the antenna and a characteristic of a voltage standing wave ratio (VSWR), which represents an antenna matching state, considerably goes bad. Also, a gain of the antenna decreases.
Generally, in a conventional mobile communication service, a bandwidth of a cellular mobile system is 70 MHz and a central frequency is 859 MHz, that is, the ratio of the bandwidth to the central frequencies (hereinafter, referred to as the bandwidth ratio) is 8.15% ((70/859)xc3x97100), and a bandwidth of a personal communication service (PCS) is 120 MHz, that is, the bandwidth ratio is 6.63% ((120/1810)xc3x97100). Since the frequency band is not wideband as set above, it is possible to use the conventional dipole structure in the cellular mobile system and the personal communication service even if such a conventional dipole structure is applied to a radiation element. However, because the frequencies of a next generation mobile communication and a personal communication service having dual band are wideband having a bandwidth of 1920 MHz to 2170 MHz, that is, the bandwidth ratio of 12.23% ((250/2028)xc3x97100) in case of the next generation mobile communication and the bandwidth of the dual band is 1750 MHz to 2170 MHz, that is, the bandwidth ratio is 21.4% ((220/1960)xc3x97100), if the conventional dipole radiation element is used as it is, it is impossible to embody a desired VWSR, a beamwidth variation between the bands and a gain variation because of the bandwidth limitation of the dipole structure.
It is, therefore, an object of the present invention to provide a wideband directional antenna by using skeleton slot or delta slot radiating elements.
In accordance with an aspect of the present invention, there is provided a wideband directional antenna in a wireless communication service, comprising: at least one radiation means, wherein the radiation means includes at least one loop, wherein one feeding point of the loop is connected to feeding means and the other feeding point is connected to a ground distributing means.
In accordance with another aspect of the present invention, there is provided a wideband directional antenna in a wireless communication service, comprising: a plurality of radiation means for a radiating radio waves, wherein one radiation means consists of two loops which are symmetrically coupled with each other sharing one side thereof; a plurality of holding means for holding and fixing the plurality of the radiation means in a predetermined position; a plurality of feeding means for feeding signals to the plurality of the radiation means; a plurality of ground distribution means for grounding the plurality of the radiating means; a plurality of power dividing means for dividing and supplying signals to the plurality of the radiation means; a plurality of impedance transforming means for matching impedances between the power dividing means and the feeding means; a reflection means for reflecting radio waves with maintaining a predetermined distance to the radiation means and fixing a plurality of configuration elements; a plurality of holding means for fixing the plurality of distribution means with maintaining a predetermined distance to the reflection means; a feeding cable for supplying signals to the power dividing means; and choke reflection means for suppressing the side lobes of the antenna, wherein the choke reflecting means are located in both sides of the reflection means in longitudinal direction.